Computer aided design (CAD) software is often used to prepare a CAD model or models representing a structure, such as a building. The CAD model can incorporate representations of physical elements, such as columns, beams, and the like that will be included in the structure. Drawings prepared from such a CAD model can be used in the actual physical construction of the corresponding structure. The CAD model may be prepared and edited by various individuals, including architects and structural engineers.
As part of a design stage or after a design is completed, a structural analysis is typically performed on a structure. Structural analysis can include the computation of deformations, deflections, or internal forces on and within solid and non-solid structures based on information such as a structure's geometry, applied loads and material properties of physical elements making up the structure. Result information incorporates results from performing the structural analysis and can incorporate, for example, displacements, axial forces, bending moments, shear forces, stresses, load reaction information, and other information. Result information can also incorporate a history of result information over time.
Load information incorporates a representation of one or more applied loads. An applied load is a force or forces applied to a component of a structure or to the structure as a whole. There are different types of applied loads. Commonly used applied loads can include constant loads known as dead loads (e.g., the weight of equipment, materials), static loads known as live loads which typically represent a one time maximum varying load on a structure (e.g., the weight of occupancy, automobile or foot traffic), loads proportional to exposed surface areas known as environmental loads (e.g., snow load, wind load, rain load), and dynamic loads. Dynamic loads typically involve dynamic effects such as from waves, ice flow, wind gusts, and earthquake motion. An applied load can be represented as a combination of different load types. Moreover, load information can represent a history of applied loads over time, such as might be caused by applying an earthquake ground motion to the foundation of a building.
Conventional analysis programs, tools, plugins or other suitable processes (hereinafter “programs”) receive as input by way of import or user creation an analytical representation of a structure and, optionally, load information. Load information can be provided to an analysis program and/or derived by the analysis program. For example, often material dead loads—such as the weight of beams and columns, are automatically calculated by the analysis program, while environmental loads are input by the user. An analytical representation of a structure is different than a representation of the physical elements, e.g., columns, beams, etc. It is an idealized mathematical model that may represent only a portion of a building such as one wing or one floor or one frame of the building. For example, an analytical representation may be a wire frame representation of the physical elements, and the wire frame elements can include or have associated properties (e.g., weight, materials, moment of inertia, cross-sectional area), member connectivity and/or end conditions (e.g., pinned, free, fixed). Typically, the analytical representation is prepared separately and can be used for other types of analyses that are performed in the design stage.
The analytical representation can be subjected to applied load simulation and the like in an analysis program to identify, for example, stress levels in the various elements. See, e.g., FIGS. 12-16. On the basis of the analysis, elements may be modified (e.g., resized or other properties changed) and the modified analytical representation reanalyzed. A commonly used approach to performing structural analysis is the finite element approach which is a numerical method that models a structure as a discrete system with a finite number of elements interconnected at a finite number of nodes.
Depending on the structure and type of analyses required, multiple analysis programs commonly need to be used. For example, special foundation analysis programs may be used to analyze different foundation configurations or variations in soil properties. Additionally, there are other programs used to analyze specialized structures such as billboards or towers that are located on the tops of buildings. Results from one analysis are often iteratively used in another analysis. For example, the combination of wind and dead loads on a building can propagate through a structure and produce resultant loads on the foundation. Those loads may be used as input to a foundation analysis program. The results of the foundation analysis may have the consequence of changing the design (or the analytical model of the design), and the cycle of building and foundation analyses is commenced again.
Any change to the size or location (i.e., displacement) of physical members or their applied loading typically needs to be manually updated between the multiple analysis and design programs. For example, foundation reactions from a seismic analysis of the structure are commonly transcribed and used as input for a foundation analysis program. The effort and coordination involved with synchronizing these displacements and loadings between programs can be significant. Any out-of-synch issues could result in an inadequate design being taken to construction.